Animal Gestation Calculator

Guinea pig Gestation Calculator

A guinea pig's gestation period is about 68 days, or roughly 2 months and 1 week, though it ranges from 59 to 72 days depending on breed and individual animal.

How to use the guinea pig gestation calculator

  1. 1. Choose what you know. Enter the breeding date to get a due date, or switch to the target due date mode to work backwards to the breeding date you need.
  2. 2. Refine the inputs. Pick the breed so the calculator uses the right average gestation length.
  3. 3. Plan around the range. Use the earliest and latest dates and the milestone timeline to schedule checks, feed changes and preparation of the birthing area.

Calculate a pup due date

What do you know?

Estimated birthing date

Thursday, 19 November 2026

Earliest

10 Nov 2026

Latest

23 Nov 2026

68 days remaining0% complete

0 of 68 days elapsed

Milestone timeline

Key Guinea pig pregnancy milestones with calculated calendar dates
DayMilestoneDate
15Pregnancy usually confirmable by gentle palpation or ultrasound27 Sept 2026
21Switch to unlimited alfalfa hay for extra calcium and protein3 Oct 2026
35Stop picking her up unless necessary; support the hindquarters if you must17 Oct 2026
45Pups become visible and their movement can be seen from outside27 Oct 2026
56Pelvic separation begins — check gently once a day7 Nov 2026
63Earliest normal birth; separate the boar now if he is still present14 Nov 2026
68Expected birth19 Nov 2026

What to do next

How long is a guinea pig's gestation period?

The average is 68 days from breeding to birthing, about 2 months and 1 week. Anything between 59 and 72 days is normal, and a typical litter is 2-4 pups. Treat the calculated date as the middle of that window rather than a fixed appointment.

Guinea pig gestation table: breeding date to birthing date

Breeding dates one week apart with the matching birthing date at 68 days.

Twelve sample Guinea pig breeding dates and their calculated due dates
Breeding dateExpected birthing date
12 Sept 202619 Nov 2026
19 Sept 202626 Nov 2026
26 Sept 20263 Dec 2026
3 Oct 202610 Dec 2026
10 Oct 202617 Dec 2026
17 Oct 202624 Dec 2026
24 Oct 202631 Dec 2026
31 Oct 20267 Jan 2027
7 Nov 202614 Jan 2027
14 Nov 202621 Jan 2027
21 Nov 202628 Jan 2027
28 Nov 20264 Feb 2027

How breed changes the birthing date

Selecting a breed swaps the average the calculator uses, which can move the birthing date by more than a week.

Guinea pig breeds and their average gestation length in days
BreedAverage daysDifference
Average68—
Large litter (4 or more pups)63-5 days
Small litter (1 to 2 pups)70+2 days

Working backwards from a target birthing date

If you want pups on the ground in a particular week, switch the calculator to target date mode and enter the date you are aiming for. It subtracts 68 days to give the breeding date to book, plus the earliest and latest service dates that still land inside your window.

Guinea pig gestation calculator FAQs

How long is a guinea pig pregnant?

About 68 days, with a normal range of 59 to 72 days. Small litters of one or two pups tend to arrive around 70 days and large litters of four or more around 63.

Why is guinea pig gestation so much longer than other rodents?

Because guinea pigs are precocial — the pups are born fully furred with open eyes and teeth, able to walk and eat solid food within a day. That development happens in the uterus, so it takes nine to ten weeks instead of three.

What is pregnancy toxaemia and how do I avoid it?

It is a metabolic crisis in the last two weeks of pregnancy, most common in overweight sows and after any interruption to feeding. Keep her eating constantly, keep her weight sensible before breeding, avoid all stress and heat, and treat refusal of food as a same-day emergency.

How can I tell birth is close?

Feel gently just in front of the genitals: the two halves of the pelvis separate to roughly a finger's width one to two days before the birth. Guinea pigs do not nest or behave dramatically, so this pelvic check is the only real warning you get.

When must the boar be separated?

Before the birth. A sow can be mated and conceive again within hours of delivering, so leaving the boar in means back-to-back pregnancies that seriously damage her health.

Is it dangerous to breed a guinea pig for the first time when she is older?

Yes. If a sow has never been pregnant before about seven months of age, her pubic symphysis fuses and cannot separate properly for birth, which makes a difficult delivery and a caesarean much more likely.

More gestation pages

Rodent gestation periods